The present invention relates to a method and a machine for making belting with a woven single-layer central portion and two tubular edge portions. Beltings of this type are disclosed in German Patent Publication No. 2,508,732. It is an object of the present invention to manufacture this type of belting at a higher speed and therefore at a lower cost than has heretofore been possible.
A belting with two tubular edge portions such as are used in safety belts in vehicles can be woven in a relatively simple manner on a shuttle ribbon weaving machine. However, such machines do not allow high production speeds due to the high mass of the shuttle and the machine elements employed to move the shuttle. Also, the shed formed on such machines is of a relatively large size and a large reed motion is necessary for the shuttle. In addition, much time is consumed for spooling the weft thread for the shuttle.
Utilization of a gripper ribbon weaving machine only slightly increases the production speed for such belts. Although the gripper has a smaller mass than the shuttle, the gripper has a considerable length in relation to the width of the woven belting so as to provide space for the passage of the tuck bobbin. This again results in the formation of a large shed and a large reed motion.
Besides the mass of the gripper, the tuck bobbin must also be moved so that, together, considerable increase in the production speed is prevented. Again, in this type of machine, the tuck thread has to be spooled.
The production speed can be raised considerably by means of the fabric structure of the present invention. According to the present invention, a needle ribbon weaving machine which is known, per se, in this art is utilized where a weft insert needle which is shorter and thinner than the gripper of the gripper machine is employed. Further, this type of machine has a knitting needle with a latch which can be readily employed to fix the weft thread loops formed by the weft inserting needle along one of the belting edges by means of a tuck thread. The tuck thread in such arrangements need not be spooled but can be fed off from a cone or cop.
For making one of the tubular edge portions there is first woven a single-layer fabric which is then closed to form the tubular edge portion in the working sequence immediately after every second double pick of the inserting needle by means of the pull of the associated weft thread. According to the present invention, one of the tubular edge portions is formed in a known manner while the opposite tubular edge portion is manufactured according to the present invention and is located on the side of the belt reached by the inserting needle moving from the first edge portion across the shed to the opposite edge of the belt.
In such structures, a knitting course must be provided at one of the belting edges. However, such knitting courses become worn during the life of the belting and if the belting is used as a safety-belt in vehicles, the edges of the belting rub against the clothes of a person wearing the belt as well as against the shackles of automatic seat belt mounting devices. If the knitting course is destroyed by such wear, the anchoring of the weft thread loops by the tuck thread is lost and the belting would be destroyed. It is especially dangerous, when the belt is used as a safety belt, where the destruction occurs at first only partially as such localized wear is unnoticed so that the resulting decrease in strength of a belt will not be detected.
Generally is also undesirable to have a thick and therefore projecting knitting course since it results in the formation of belting edges which are very rough and can result in discomfort to a wearer.
It is insufficient merely to displace the knitting course from the medium plane of the belting to the upper or lower attaching line or joint of the second tubular edge portion since the knitting course itself would then be subject to much wear and would abrade against the clothing of the person wearing the belt. provide
It is therefore an important object of the present invention that the foregoing disadvantages be obviated and a strong yet comfortable belting structure be provided. To this end, the tuck thread loops are drawn by the weft loops a certain distance into the central portion of the belt fabric. For example, the tuck thread loops may be drawn a distance of approximately 5 mm within the central portion so that, in effect, for this narrow strip, the weft threads are replaced by tuck threads. This will not change the character of the fabric in the central portion of the belt in any practical sense and will not be noticed. The knitting course will therefore no longer be occupied with the tops or ends of the weft loops and the two ends of the tuck thread loops which are interlocked with an associated end of a weft loop as these sections of the threads are displaced into the single-layer central portion of the fabric. As a result, the thickness of the knitting course is considerably reduced and will not project beyond the normal thickness of the fabric. Also, a soft tubular edge portion will be obtained and the knitting course will not be subjected to any greater wear than the other portions of the belting.
In an alternative embodiment, where it is desired to prevent laddering in the fabric which can destroy the belt, the present invention employs an additional thread, termed a locking thread, which is worked into the knitting course by means of the knitting needle. Following the method of the present invention, even though the use of an interlocking thread renders the knitting course thicker, the knitting course can still be worked into the fabric to a sufficient depth so that it will not noticeably project.
By a further modification, according to the present invention, a normal needle ribbon weaving machine is made suitable for carrying out the method of the present invention by inserting a transmission in the tuck thread feeding device.
Since the single-layer central portion of the belt and the second tubular edge portion have twice the number of tuck threads per meter as compared with the number of weft threads, the tuck thread should be twice as fine as the weft thread. The choice of the weft threads according to the desired characteristics of the belting is therefore limited. In accordance with a further embodiment of the present invention, a belting can be produced without the use of a tuck thread but which retains the above-stated advantageous properties of the belt. According to this embodiment, a pick is always knitted with the preceding pick and with an interlocking thread in making the knitting course. Surprisingly, the knitting course can be inserted easily and with sufficient depth into the belting if the interlocking thread is laid into the head of the knitting needle from a point vertically above, that is, in a downward direction relative to the belt as related to the normal arrangement of a ribbon weaving machine. The single layer ribbon portion which is first made is folded around to the upside and is then drawn onto the central portion. The upper or topside of the belting is therefore that side on which the single layer ribbon portion for making the tubular edge portion is fixed to the central portion of the belting by means of the knitting course.
Conventional needle ribbon weaving machines do not allow the interlocking thread to be guided above the knitting needle and do not allow the feeding of the interlocking thread from vertically above to the head of the knitting needle. According to the present invention, the needle ribbon weaving machine is improved and made suitable for this type of feeding. In particular, during the necessary rocking motion of the knitting needle with its needle holder, an elastic thread-guide is bent in such a way that the interlocking thread guided by the longitudinal eye is laid into the head of the knitting needle in a correct manner from a point vertically above.
The foregoing and other objects of the present invention will become apparent as consideration is given to the following detailed description taken in conjunction with the accompanying drawings, in which: